// system.cc
//	Nachos initialization and cleanup routines.
//
// Copyright (c) 1992-1993 The Regents of the University of California.
// All rights reserved.  See copyright.h for copyright notice and limitation
// of liability and disclaimer of warranty provisions.

#include "copyright.h"
#include "system.h"

// This defines *all* of the global data structures used by Nachos.
// These are all initialized and de-allocated by this file.

Thread *currentThread;			// the thread we are running now
Thread *threadToBeDestroyed;  		// the thread that just finished
Scheduler *scheduler;			// the ready list
Interrupt *interrupt;			// interrupt status
Statistics *stats;			// performance metrics
Timer *timer;				// the hardware timer device,
// for invoking context switches

#ifdef FILESYS_NEEDED
FileSystem  *fileSystem;
SynchDisk* synchDisk;
#endif

#ifdef FILESYS
#endif

#ifdef USER_PROGRAM	// requires either FILESYS or FILESYS_STUB
Machine *machine;	// user program memory and registers
#endif

#ifdef NETWORK
PostOffice *postOffice;
#endif


// External definition, to allow us to take a pointer to this function
extern void Cleanup();


//----------------------------------------------------------------------
// TimerInterruptHandler
// 	Interrupt handler for the timer device.  The timer device is
//	set up to interrupt the CPU periodically (once every TimerTicks).
//	This routine is called each time there is a timer interrupt,
//	with interrupts disabled.
//
//	Note that instead of calling Yield() directly (which would
//	suspend the interrupt handler, not the interrupted thread
//	which is what we wanted to context switch), we set a flag
//	so that once the interrupt handler is done, it will appear as
//	if the interrupted thread called Yield at the point it is
//	was interrupted.
//
//	"dummy" is because every interrupt handler takes one argument,
//		whether it needs it or not.
//----------------------------------------------------------------------
static void
TimerInterruptHandler(int dummy) {
    if (interrupt->getStatus() != IdleMode) {
        interrupt->YieldOnReturn();
    }
}

//----------------------------------------------------------------------
// Initialize
// 	Initialize Nachos global data structures.  Interpret command
//	line arguments in order to determine flags for the initialization.
//
//	"argc" is the number of command line arguments (including the name
//		of the command) -- ex: "nachos -d +" -> argc = 3
//	"argv" is an array of strings, one for each command line argument
//		ex: "nachos -d +" -> argv = {"nachos", "-d", "+"}
//----------------------------------------------------------------------
void
Initialize(int argc, char **argv) {
    int argCount;
    char* debugArgs = "";
    bool randomYield = FALSE;

#ifdef USER_PROGRAM
    bool debugUserProg = FALSE;	// single step user program
#endif
#ifdef FILESYS_NEEDED
    bool format = FALSE;	// format disk
#endif
#ifdef NETWORK
    double rely = 1;		// network reliability
    int netname = 0;		// UNIX socket name
#endif

    for (argc--, argv++; argc > 0; argc -= argCount, argv += argCount) {
        argCount = 1;
        if (!strcmp(*argv, "-d")) {
            if (argc == 1) {
                debugArgs = "+";    // turn on all debug flags
            } else {
                debugArgs = *(argv + 1);
                argCount = 2;
            }
        } else if (!strcmp(*argv, "-rs")) {
            ASSERT(argc > 1);
            RandomInit(atoi(*(argv + 1)));	// initialize pseudo-random
            // number generator
            randomYield = TRUE;
            argCount = 2;
        }
#ifdef USER_PROGRAM
        if (!strcmp(*argv, "-s")) {
            debugUserProg = TRUE;
        }
#endif
#ifdef FILESYS_NEEDED
        if (!strcmp(*argv, "-f")) {
            format = TRUE;
        }
#endif
#ifdef NETWORK
        if (!strcmp(*argv, "-l")) {
            ASSERT(argc > 1);
            rely = atof(*(argv + 1));
            argCount = 2;
        } else if (!strcmp(*argv, "-m")) {
            ASSERT(argc > 1);
            netname = atoi(*(argv + 1));
            argCount = 2;
        }
#endif
    }

    DebugInit(debugArgs);			// initialize DEBUG messages
    stats = new Statistics();			// collect statistics
    interrupt = new Interrupt;			// start up interrupt handling
    scheduler = new Scheduler();		// initialize the ready queue
    if (randomYield) {			// start the timer (if needed)
        timer = new Timer(TimerInterruptHandler, 0, randomYield);
    }

    threadToBeDestroyed = NULL;

    // We didn't explicitly allocate the current thread we are running in.
    // But if it ever tries to give up the CPU, we better have a Thread
    // object to save its state.
    currentThread = new Thread("main");
    currentThread->setStatus(RUNNING);

    interrupt->Enable();
    CallOnUserAbort(Cleanup);			// if user hits ctl-C

#ifdef USER_PROGRAM
    machine = new Machine(debugUserProg);	// this must come first
#endif

#ifdef FILESYS
    synchDisk = new SynchDisk("DISK");
#endif

#ifdef FILESYS_NEEDED
    fileSystem = new FileSystem(format);
#endif

#ifdef NETWORK
    postOffice = new PostOffice(netname, rely, 10);
#endif
}

//----------------------------------------------------------------------
// Cleanup
// 	Nachos is halting.  De-allocate global data structures.
//----------------------------------------------------------------------
void
Cleanup() {
    printf("\nCleaning up...\n");
#ifdef NETWORK
    delete postOffice;
#endif

#ifdef USER_PROGRAM
    delete machine;
#endif

#ifdef FILESYS_NEEDED
    delete fileSystem;
#endif

#ifdef FILESYS
    delete synchDisk;
#endif

    delete timer;
    delete scheduler;
    delete interrupt;

    Exit(0);
}

